Fig. 3. PTBP1 levels increase in sensory axons following nerve crush.

(A) PTBP1 protein expression in sciatic nerve (SN) axoplasm under naive (na) and injury (inj) conditions. Detection by WB. PTBP1 levels were normalized to ERK1/2 (ERK), and the data are shown as FC to naive (red dashed line). Individual data points with mean ± SEM, one-way analysis of variance (ANOVA) with Dunnett’s multiple comparisons test against naive control condition, **P < 0.01, n = 3 mice for each time point. (B) Representative images of SN cross sections from naive nerve and 7 days after crush injury. Axonal PTBP1 is shown in magenta hot scale (0 to 255), axonal profiles positive for TUJ1 indicated with white lines. Scale bars, 5 μm. (C) Quantification of axonal PTBP1 signal in TUJ1-positive axons of different sizes (axon area bins: 0 to 1, 1 to 2, 2 to 5, and 5 to 10μm²). PTBP1 intensity is shown as FC to naive (red dashed line), individual data points with mean ± SEM, two-way repeated measure (RM) ANOVA, ****P < 0.0001, Sidak’s multiple comparisons test, **P< 0.01, *P < 0.05, n = 3 (>700 axons per mouse for each size category). (D) PTBP1 protein expression in cell bodies of DRG. WB of PTBP1 with normalization to GAPDH, shown as FC to naive (red dashed line). Individual data points with mean ± SEM, one-way ANOVA with Tukey’s multiple comparisons test, not significant, n = 3 to 4 mice for each time point. (E) Representative images of DRG tissue sections from naive, 3 and 7 days after SN crush. Scale bars, 20 μm. (F) Quantification of nuclear PTBP1 signal in DRG neurons (summary of all cell sizes, NHF⁺ and NHF⁻ cells). Individual data points with mean ± SEM, one-way ANOVA with Tukey’s multiple comparisons test, not significant, n = 3 to 7 mice (>95 cells per mouse).